noun, plural: sex chromosomes
A somatic cell contains a genome comprised of paired chromosomes: the autosomes and sex chromosomes. A sex chromosome is a type of chromosome responsible for the chromosomal determination of the sex of an individual, e.g. whether a female or a male. Sex determination is based on the genes responsible for the development of the corresponding sexual characteristics of the organism. The sex chromosome occurs in pairs in somatic cells while singly in sex cells (gametes).
In humans, there are two forms of sex chromosomes: the X chromosome and the Y chromosome. A pair of X and Y results in a chromosomal male whereas a combination of X and X results in a chromosomal female. Because they differ in form, size, or behavior, they are also referred to as heterotypical chromosomes or heterochromosomes. This XX/XY sex-determination system is one of the most familiar sex-determination systems and is applicable in human beings and many other mammals. In this system, the sex of an organism is determined by the sex chromosomes since these chromosomes bear the genes that control the development of reproductive organs and other sexual characteristics of an organism.
- heterotypical chromosome